When does a dynamically loaded JavaScript library become available?

Question

I wrote JavaScript library to use FileSaver.js and its associated libraries. However, I don\'t want to always load FileSaver.js whenever someone wants to use my library. And

Answer 1

the Holistic solution is to use a module system. AMD is (in-my-just-an-observation-please-dont-start-a-holy-war-opinion) probably the most commonly used system for browser async code loading. AMD is just a spec, but something like require.js is a very popular tool for using AMD modules.

The idea being that you can define dependencies between your modules, and require.js will go fetch them if need be. The general idea is to mimic the import/namespace functionality of other languages (like java, C#, or python). "code sharing" i think is the term?

simply put you have all your code in a callback function that runs once the dependencies are loaded, so you can be sure the needed objects and methods are present.

update 2015

just an addendum. while the info above is still correct, front end code management is moving quickly toward solutions like Webpack and Browserify, which bundle and concatenate code of any module type and both have dynamic code loading capabilities (webpack calls this code splitting). That coupled with the exponential growth of npm for dependency management is beginning to make AMD less relevant.